"Desertification is the persistent degradation of dryland ecosystems by variations in climate and human activities." It turns drylands into deserts, places filled only with rocks, soil, and sand. It also increases the "frequency of sand and dust storms" and "flooding due to inadequate drainage or poor irrigation practices."

In the year 2000, it occupied about 41% of the Earth's surface, and now currently covers huge proportions of most of the world, excluding Antarctica, with 10% to 20% of it already degraded.

drylandsmap.jpg

This occurred due to the vast division between human demands and the availability of natural resources. Once we have taken all that we can from the land, it goes into a state which nothing can possibly thrive. It is at this stage that the human population will run into great problems since we take the majority of our basic needs from drylands.

Example
In the 1930's, during the Great Depression, parts of the Great Plains, which are located in the United States, turned into a "Dust Bowl,"
which was caused by continuous droughts, floods, and dirt and dust storms over many years. This caused people to become more aware of the dangers of neglecting care for the environment, and introduced new practices, such as soil conservation, to help to prevent this disaster from recurring across the whole country.

To prevent, or maybe even reverse the effects of desertification (though it has not yet been confirmed capable), a huge effort must be put in to maintain the way that we treat the land, and an increase in preventing or monitoring the factors that can cause desertification naturally.

Bibliography
http://www.greenfacts.org/en/desertification/#1
http://pubs.usgs.gov/gip/deserts/desertification/
http://www.ccccok.org/museum/dustbowl.html
http://www.greenfacts.org/en/desertification/l-2/1-define-desertification.htm#0 (Image)
http://www.ace.mmu.ac.uk/eae/Global_Warming/Older/Desertification.html